[RE-wrenches] not sure what's going on here

[Bob-O Schultze]

Ron,
It certainly sounds like a failed diode (there are two) to me. Usually they fail open, but it isn't unheard of that they might just avalanche when they see the current of the other PVs. Solarworld would probably replace it under warranty IF you return the dead module to them. How the hell do you do that? I'd tell him to call them and see if they will let him record whatever test procedures they want to see. This assumes, of course, that your DIY guy has a decent DMM, etc. He might get lucky.
It's often a good faith gesture to help out a DIY in a situation like this, but if I were you, I'd make it very clear that this is a one-time deal. Explain that you are a pro who gets paid for your hard-won knowledge and expertise. If he is like most DIY-ers, that will be the last you hear from him. A good deal for you- you really don't want him as a BFF who feels like he can ring you up every time he has a question, but continues to buy his stuff from Cheaper-than-you-can-imagine.com Ya know?
Bob-O  
On May 10, 2013, at 4:33 PM, Ron @ earthRight Solar wrote:

Hi Wrenches, 

Wondering if anyone can shed some light on this. I have a customer who self installed 4 x 165w Solarworld panels a few years ago (2008). It's a 12v nom. battery and the panels are wired in parallel. They've been working fine for five years on a full time household using a 3024i Blue Sky controller albeit driving it well beyond it's max PV power recommendation as currently published by Blue Sky. 

However, now one of the panels has dropped from approx. 30-35v output to 13v. When the failed panel is removed from the string the three remaining panels come back to normal voltage and amp output but after about 15 minutes drop down to around 13v on the Blue Sky display - even though the individual output from each panel when unhooked and tested in full sun show about 35v. After turning the system off and on again a few minutes later the normal voltages return but drop again in about 15 min. The failed panel stays at 13v, does not recover.

I'm trying to do a little pro bono diagnostic for the guy who lives back in the bush. I haven't been to the site but asked him to carefully check all the wiring and he says it's fine. So two questions. First- is there a diode in the failed Solarworld (sealed J box) that could have failed and if so is it repairable? Second, any ideas what could explain the intermittent drop in voltage output of the remaining three?

Ron Young
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